Glossary

Joint

The juncture of two or more bones in the body. The human body contains more than 150 joints. Some of them, such those where the bones of the skull meet, are rigid. Others, such as the knee or wrist, allow the body to move in many different positions.

Juvenile arthritis

Any form of arthritis diagnosed in a child under age 16.

Juvenile rheumatoid arthritis (JRA)

The most common type of arthritis in children. There are three different forms of JRA: systemic-onset, polyarticular-onset and pauciarticular-onset. Each type is differentiated primarily by the number of joints affected.